Bug ID: JDK-8294967 C2 fails with assert(!n->is_Store() && !n->is_LoadStore()) failed: no node with a side effect

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JDK 20
20Unresolved

Running the attached JavaFuzzer-generated Java program (Test.java) on a debug JDK build as follows:

$ java -Xcomp -XX:-TieredCompilation -XX:CompileOnly=Test::test Test.java

Results in the following assertion failure:

# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (../../src/hotspot/share/opto/loopopts.cpp:1605), pid=439963, tid=439976
#  assert(!n->is_Store() && !n->is_LoadStore()) failed: no node with a side effect
#
# JRE version: OpenJDK Runtime Environment (20.0) (fastdebug build 20-internal-adhoc.rocastan.open)
# Java VM: OpenJDK 64-Bit Server VM (fastdebug 20-internal-adhoc.rocastan.open, compiled mode, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V  [libjvm.so+0x14dbebf]  PhaseIdealLoop::try_sink_out_of_loop(Node*)+0xa0f

I think this is likely a case of JDK-8288981 where unswitching happens after pre/main/post loop are created. Then pre/main/post and unrolling happens on one of the new main loops. Too much unrolling causes a CastII to become top which in turns causes a store to have no memory phi that keeps it in a loop (and the assert fires). This should be caught by skeleton predicates but isn't because they are lost on the way (they are not copied from the main loop when unswitching happens).
07-10-2022
ILW = assertion failure in debug build; JavaFuzzer-generated test case; disable compilation of affected method = MMM = P3
07-10-2022
[~roland] since you have worked on related assertion failures before, could you have a look? Thanks!
07-10-2022
The failure can be reproduced first on JDK 19 b26.
07-10-2022

Relates :	JDK-8286625 - C2 fails with assert(!n->is_Store() && !n->is_LoadStore()) failed: no node with a side effect
Relates :	JDK-8288981 - C2: Fix issues with skeleton predicates